1. Field of the Invention
The present invention relates generally to proximity sensor circuits, and particularly to a device to monitor distance between people that provides for measuring a pre-defined distance between a first person and other persons, the device alerting the user when the pre-defined distance has been breached or violated for more than a pre-determined time.
2. Description of the Related Art
After a patient who has been treated with therapeutic doses of radioactive iodine (I-131) is discharged, the radiation from the doses can be potentially harmful to those in close proximity to the patient. Greatest concern is given to family members, individuals close to the patient, as well as health care professionals and the environment. It was found that those who are close to the patient should not exceed 5 mSv of cumulative radiation exposure per treatment episode.
The thyroid gland produces hormones that affect heart rate, blood pressure, body temperature, and weight. One in 92 men and women will be diagnosed with thyroid cancer during their lifetime. About 60,200 new cases of thyroid cancer will be diagnosed in 2013, with an estimated 1,850 deaths. Of the estimated 60,200 new cases of thyroid cancer, it is estimated that 45,310 will be women, and 14,910 will be men. The median age for thyroid cancer is 50 years of age.
Another common thyroid disorder, hyperthyroidism, occurs when the patient has excessive amounts of thyroid hormones due to several different diseases, such as Graves' disease, toxic multinodular goiter, or toxic adenoma. Common symptoms of hyperthyroidism include excessive sweating, heat intolerance, increased bowel movements, tremor, nervousness, rapid heart rate, weight loss, fatigue and irregular menstrual flow. Hyperthyroidism is much more common than thyroid cancer, with approximately 2% of women and 0.2% of men experiencing cases of hyperthyroidism at some point in their lifetime.
Doses of I-131 as a method of systematic radiation therapy has successfully treated hyperthyroidism and thyroid cancer for more than 60 years. Radioiodine is the treatment of choice for radiation therapy in the United States, United Kingdom, and Canada because it is relatively inexpensive and very effective compared to other treatments. Radioactive iodine works well for thyroid treatment because the thyroid cells naturally take up iodine, allowing the radioactive iodine to damage the DNA of the cancerous cells.
One of the risks of radioactive iodine therapy is that the patient becomes temporarily radioactive after treatment. While most of the radioactive iodine is excreted through urine, the patient can radiate gamma rays from the decaying I-131. These gamma rays can be particularly harmful for pregnant women and children standing near the iodine therapy patient due to their higher risk of developing cancer.
The chance for developing fatal cancer due to exposure to radiation increases by 5% per Sievert of radiation accumulated, and the odds of developing cancer are 2 to 3 times higher for children. Although the dosage of secondary radiation to other persons from radioiodine therapy patients is to the order of micro Sieverts per hour, patients must be sure that exposure to children and pregnant women is minimized due to their increased chance of developing cancer after exposure to radiation.
In order to minimize secondary radiation to other persons, doctors set forth strict guidelines for patient behavior following treatment. Patients are instructed to stay one meter away from persons at home and two meters away from someone if they are near them for an extended period of time. Also, it is recommended that children under two-years of age are cared for in a separate household if the parent received radioiodine because children often require physical attention, which the parent cannot give following treatment.
Patients must follow more extensive guidelines regarding public interactions, including avoiding public transportation, avoiding work if it is necessary to stand or sit near coworkers for an extended time, and disposing of tissues or other waste items properly. The timeframe that a patient must follow these guidelines varies from 24 hours to six weeks, depending on the dosage of radioactive iodine. For up to six weeks, patients should be conscious of their distance to others within the aforementioned timeframe, especially with respect to children and pregnant women. Nevertheless, patients may inadvertently come into proximity with persons at high risk of adverse consequences from secondary radiation, or inadvertently remain in such proximity for too long a period of time.
Thus, a device to monitor distance between people solving the aforementioned problems is desired.